Blends of ceramic material and polyester resin are marketed by the Tanner Chemical Company under the trademarks CERFOAM and CERPOL as molding compositions for a variety of end use applications. These molding compositions are described in U.S. Pat. Nos. 3,978,018, 4,013,614 and 4,011,195 issued to James M. Self. These new molding compositions are two-part systems, a part "A" consisting of a general purpose polyester resin in admixture with a filler such as hydrated alumina and/or calcium carbonate and a part "B" containing sodium silicate or aqueous alkali stabilized collodial silica, hydrated alumina and a catalyst. These new molding compositions show great promise for replacing conventional epoxy/fiberglass materials used as building panels, shower and tub enclosures, etc.
Notwithstanding the significant cost advantages over conventional fiberglass compositions, in terms of both raw material costs and processing costs, the new ceramic/polyester molding compositions have not previously been commercially utilized in processes where such compositions would come into direct contact with a mold surface. The problem inhibiting such utilization is that the ceramic/polyester molding compositions have proven to be unusually tenacious in their adherence to mold surfaces. While a great number of excellent mold release agents are commercially available, the numerous commercial agents which have been tested in the molding of the ceramic/polyester resins have proven to be totally unsatisfactory. Specifically, attempts to mold such compositions with microcrystalline waxes, solutions of co-polymers of ethylene and vinyl acetate, and various combinations of the foregoing, proved to be largely ineffective as mold release agents in the molding of the ceramic/polyester compositions. The use of silicone release agents is impractical because the film remaining on the surface of the molded part precludes the painting of the molded surface. Polyethylene dissolved in toluene proved to be a very poor release agent for such systems and various mineral oils which were tested as release agents were totally inoperative.
Aside from the problem of release per se, the conventional technique for applying mold release agents to molds previous to the molding of tubs, shower stalls, etc. is itself a problem. According to conventional fiber-glass molding practice, a wax-like release agent is applied to the mold surface and buffed down to a very thin coating after each application. Thus, the conventional technique is labor intensive and time consuming.
In the present invention, in attempting to find a suitable mold release agent for CERPOL and CERFOAM molding compositions, environmental considerations were also taken into account. Because of the imposition of stricter laws regarding the working environment and clean air standards, a need for solvent-free mold release agents exists in the industry.